The Drengin Empire apparently train their diplomats by putting all of them in a room, having half of them wear rubber masks of 'food races' and pretend to act like they are said species, and watch the resulting interaction.
In 3, the entire Drengin tech tree. The other factions explain what each tech does with a tongue-in-cheek sense of humor. The Drengin, on the other hand, cast all subtlety to the wind and eat it, demonstrating that they often literally beat their technology into existence.
"The research slavelings complain that we can't see any further because of the nature of this universe. We have ordered the universe be whipped, but in the meantime, have found a few more efficiencies we could implement."
"We stationed a huge Drengin with an axe in the research labs, standing there, not saying a word. Almost immediately the researchers saw several places to improve our sensors. What a lucky coincidence."
""Are all these parts really necessary?" we asked the research slavelings of our life support systems. They were, but we removed a few anyways."